PROJECT SUMMARY/ABSTRACT Eleven investigators representing ~20% of the Basic Medical Sciences Faculty of the University of South Alabama College of Medicine are seeking support under the Shared Instrumentation Grant Program to acquire an XFe24 extracellular flux analyzer. These investigators are supported by 16 NIH grants (~75% of all NIH grants issued to Basic Medical Sciences faculty). Almost 50% of all currently funded NIH awards to Basic Medical Sciences Faculty will directly benefit from requested XFe24, and are participating. The number of participants on this revised application has increased by ~50% (7 to 11) compared to A0. XFe24 provides an unrivaled combination of features, including high sample throughput, t h e ability to conduct studies in both cultured cells and tissue samples, and simultaneous measurement of two key parameters representative of cellular bioenergetics: respiration (oxygen consumption) and extracellular acidification. Additional features include widely compatible software and an improved sensor design that dramatically improves signal stability and reproducibility when measuring extracellular acidification. The current application targets key research projects at the USA College of Medicine that critically need the cutting-edge capabilities of the XFe24. These high-priority projects include ongoing studies in the areas of Mitochondrial Disease, Mitochondrial DNA Damage and Repair, Vascular Physiology and Pathology, Metabolism, Host-Pathogen Interactions, Immunology, Cancer Biology, Environmental Toxicology and Cell Biology. Major users include Drs. Alexeyev, Sobol, Stevens, Honkanen, Lim, Gillespie, and Audia/Alvarez, whose projects focus on mitochondrial disease, cancer biology/environmental toxicology, vascular endothelial biology, metabolism, smooth muscle biology, mitochondrial DNA damage and repair and host-pathogen interactions, respectively. Acquisition of the XFe24 is justified by: 1) the age (9 years) of the available XF24 instrument, 2) increasing risk of a catastrophic failure in combination with 3) the End of Guaranteed Support for this instrument by the manufacturer, 4) incompatibility of the available instrument with commercial glycolytic flux assays, and 5) increasing demand among faculty for the XFe24's capabilities. In summary, procurement of the XFe24 instrument is critical to sustaining ongoing NIH-funded studies at the USA College of Medicine, to broadening their scope, and to fostering t h e development of new projects by junior investigators. Research in the areas of Mitochondrial Disease, Mitochondrial DNA Damage and Repair, Vascular Physiology and Pathology, Metabolism, Host-Pathogen Interactions, Immunology, Cancer Biology and Cell Biology described within this application depends critically on the availability of this equipment to remain competitive and to continue a long track record of scientific productivity.